Depending on the make and model of your Android phone, you might be able to use GrapheneOS which will vastly improve your situation. Use it together with privacy respecting apps and you’ll be a long way towards reclaiming your mobile privacy. You can also buy Android phones that are pre-configured with Graphene on them on ebay but you are obviously a running a risk.
Desktop/laptop you will need to move to Linux. Mint is (in my opinion) a very good option if you’re new to Linux as it is privacy respecting and looks/acts in a very Windows type way. Like most Linux distributions, you can even try it without installing it by downloading and burning an ISO to a USB pen/stick drive. Here’s a YT tutorial on doing that (also covers going on to install Mint).
Switch browsers to Firefox and install uBlockOrigin, LibRedirect and Firefox Multi Containers add-ons. Switch to a privacy friendly search engine such as DuckDuckGo, Startpage or a SearX instance.
Migrate your email to an encrypted privacy respecting provider such as Tuta (recently changed their name from Tutanota) and stop using things like OneDrive or Dropbox, instead use a service like ProtonDrive or Filen.
Use a decent VPN like Mullvad on all your devices. This not only protects your ISP from seeing what you’re doing it also means you’re using their DNS, which you can configure to block trackers, adverts and a few other things (at DNS level, you’ll still need uBlockOrigin in your browser). It doesn’t offer as much control as PiHole or AdGuard but it’s a lot less complicated to set up.